This multicenter clinical trial will evaluate the safety & efficacy of a new formulation recombinant antihemophilic factor (Kogenate-2) in previously treated subjects with severe hemophilia A. Recombinant AHF (Kogenate) was developed with the goal of optimizing the safety of factor replacement products for treatment of hemophilia A. Because of public concerns about products containing albumin, Kogenate-2 was produced without albumin and with an optimized purification process. It will be studied in comparison with Kogenate, and then alone. The enrollment for Stage I and II/III have been met.